Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 630 PM EST Sat Mar 01 2025 Valid 12Z Wed Mar 05 2025 - 12Z Sun Mar 09 2025 ...A series of lows may bring enhanced precipitation and gusty winds into coastal areas of Alaska next week... ...Overview... An upper ridge stretching northwest from Canada into Southeast Alaska and the Mainland into Wednesday will gradually be pushed east as upper troughing develops from a Pacific upper low with Arctic energy feeding in. Possibly several surface lows supported by the troughing aloft and moist Pacific inflow will allow for rounds of precipitation to affect the southern coast, likely heaviest in the Kenai Peninsula through Wednesday-Thursday, and expanding into Southeast Alaska mid-late week. Strong winds may also be a threat especially over maritime areas at times. Additionally, northerly flow on the backside of the lows may produce gusty winds through the Bering Strait to St. Lawrence Island and farther south through the Aleutians and Alaska Peninsula. Then by late week into next weekend, mean upper ridging will track through the Aleutians/Bering Sea, while another upper/surface low moves into the Bering Sea behind it and spreads winds and precipitation to the Aleutians. The forecast pattern will favor widespread above normal temperatures through late week, but temperatures will cool into next weekend with northerly flow behind the trough. ...Guidance Evaluation and Preferences... Model and ensemble guidance is in generally good agreement with the pattern described above. Guidance struggles more with the smaller scale details of the embedded vort maxes and surface lows though. The surface pattern is likely to be complex through midweek with multiple low centers across the northern Pacific to Aleutians and Alaska Peninsula and southern Bering Sea, which all have model spread. Today's guidance is slower to show a more consolidated low compared to a day ago, as most guidance favors a possibly moderately deep surface low in the northeast Pacific by Friday as a spoke of the trough aloft has embedded upper energy to support it. The ECMWF, CMC, UKMET, and ICON all indicate a pattern like this, but GFS runs are weaker with the upper energy and thus the surface low there as they hold back most energy farther west. Tended to prefer the non-GFS guidance low position but without showing a low as strong as some guidance, so the 00Z EC ensemble mean worked as a good proxy. There is also model spread in how fast the low weakens; the ECMWF is slowest to do so. Farther north, today's guidance is more agreeable that an Arctic upper low should stay north of the state through late week. Into the weekend though, GFS runs end up showing an Arctic upper low and surface low drifting southeast toward the North Slope unlike other guidance. Regardless some Arctic energy is forecast to filter into the Aleutians to Alaska Peninsula upper low to form the broader trough starting atop western Alaska moving east. Models are in good agreement in principle with the trough deepening and shifting east, while an upper ridge pushes through the Aleutians Friday-Saturday. There is fairly good consensus upstream for an upper low and potentially a strong surface reflection to move across the western Bering Sea next weekend. Interestingly the general deterministic model consensus in the low position is northwest of the ensemble mean consensus by next Sunday, so there is certainly timing/placement spread despite the agreement in this low's existence. The WPC forecast favored a blend of mainly deterministic models with a tilt toward the ECMWF early in the period. As the period progressed, increased the proportion of ensemble means to just over half by Days 7-8. ...Weather/Hazards Highlights... Multiple surface lows and sufficient moisture with Pacific inflow will maintain persistent moderate to locally heavy precipitation along the southern coast of the state from the Alaska Peninsula and Kodiak Island toward the Kenai Peninsula and Prince William Sound into Wednesday or Thursday. The heaviest amounts are likely to be in the favored southern part of the Kenai Peninsula, with multiple days of moderate to heavy precipitation possibly leading to hazardous conditions. The focus for precipitation is likely to expand into Southeast Alaska around Thursday or Friday with potential for a more consolidated surface low. Precipitation chances are forecast to lessen into the weekend as the trough aloft pushes through. The northern Pacific and vicinity surface lows may also cause periods of moderate to strong winds for the Gulf and perhaps even spreading into coastal areas Wednesday-Friday. Periods of light snow are also possible farther north, especially in the western Mainland on Wednesday as energy drifts southward. This could also cause brisk to strong northerly winds through the Bering Strait and St. Lawrence Island and possibly cause some maritime hazards or perhaps localized blizzard conditions on land. Some light snow could spread across much of the Interior especially Thursday and Friday. Deep layer northerly flow is likely across the Aleutians to Alaska Peninsula Thursday-Saturday on the backside of the trough, which could cause gap winds in favored areas. Then by next weekend, the next low approaching the Aleutians may lead to strong southerly winds and precipitation chances there. Much of Alaska will remain much milder than normal through much of next week. The Mainland can expect temperatures 10 to 20 degrees above average with highs near 40F in Anchorage and Fairbanks Wednesday-Thursday. Southeast Alaska can expect temperatures generally 10 to 15 degrees above normal. Temperatures start to cool down Friday, and cooler weather will reach much of the state over the weekend with the northerly flow behind the trough. Tate Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can also be found at: https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html